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Wild chimps look both ways before crossing roads

By Andy Coghlan

Video: Wild chimps take care before crossing the road

Screech! Bang! It’s the sound we all dread when crossing busy roads. Now, it turns out that like us, wild chimpanzees learn to respect roads, adopting the same cautious drills as humans, including looking both ways to check for traffic.

In a 29-month survey, researchers observed and recorded 20 instances of wild chimps crossing a busy road in Sebitoli, in the northern part of Uganda’s Kibale National Park. They watched 122 chimps cross the highway used by 90 vehicles an hour, many speeding at 70 to 100 kilometres an hour.

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It’s the first report on how chimpanzees behave crossing a very busy asphalt road, says Marie Cibot of the National Museum of Natural History in Paris. “We’ve described chimpanzee behaviour facing a dangerous situation never described before,” she says, pointing out that earlier studies looked at narrower, unpaved and less busy roads.

Extra vigilance

Chimps are exceptionally cautious when they cross the road. Ninety-two per cent of them looked right, left, or both ways before or during crossing, and 57 per cent ran across – showing that they knew the value of reaching the other side as quickly as possible.

Alpha males led and organised 83 per cent of the road-crossing posses, compared with only 51 per cent of tree-climbing expeditions in the forest studied in parallel. This implies that they recognised the importance of extra vigilance during road crossings.

There was also evidence that healthy and dominant chimps often made sure that stragglers or more vulnerable members of the group crossed safely. Some 86 per cent of the healthy chimps looked back or stopped when at least one vulnerable individual, such as an infant or injured chimp, trailed behind.

“At Sebitoli, chimpanzees tended to split into smaller subgroups when crossing, whereas chimpanzees at Bossou often, but not always, crossed in progression lines,” says Hockings. “This might be down to a higher intensity and speed of traffic at Sebitoli, forcing chimpanzees to split up.”

Cibot now hopes to work with the Ugandan authorities to test new safety measures. “We aim to test mitigation measures such as bridges, underpasses, reduced speed limits, speed-bumps and police patrols in the area,” she says. “Road infrastructure is spreading throughout Africa to support regional development, industry and tourism, and studying chimpanzee adaptation facing roads represents a way to reduce the risk of collisions.”